Helicopter drip pan apparatus and method of making and using such an apparatus

ABSTRACT

A drip pan apparatus for a helicopter includes a frame and a drip pan. The frame is secured to a skirt on the airframe of the helicopter. The apparatus includes a drip pan for cooperation with a frame to cover an access opening to a transmission. The drip pan includes a substantially planar member of a fiber-reinforced composite and has a seal surface that is configured to cooperate with a seal surface of the frame. A seal member may be disposed between the substantially planar member and the frame to form a fluid-tight seal. The fiber-reinforced composite may be a carbon fiber-reinforced composite. A method of making the drip pan apparatus includes placing a plurality of sheets of an uncured fiber-reinforced composite material on one another to form an uncured stack. The uncured stack is then cured. A frame and a drip pan may be cut from the cured stack.

CROSS REFERENCE TO RELATED CASES

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 61/495,155 filed Jun. 9, 2011, the disclosure of which isincorporated by reference herein in its entirety.

FIELD OF THE INVENTION

This invention relates to a drip pan, and more specifically to drip pansand other apparatuses for use on a helicopter.

BACKGROUND OF THE INVENTION

Larger helicopters, in general, have several features in common in abasic configuration or layout. For instance, a typical helicopter willhave a cabin section rearward of the pilot's cockpit or flight deck andwhich is used to transport people, cargo or both. In addition, thehelicopter will have an engine compartment, which is located typicallyabove and to the rear of the pilot's cockpit or flight deck and abovethe cabin section. The engine compartment typically houses two primarycomponents, at least one engine and a rotor transmission at leastpartially contained within a transmission housing.

Both the engine and the rotor transmission contain numerous fluids, suchas petroleum-based lubricants, that are critical to the operation of theengine and the transmission. These fluids inevitably leak from variouslocations in the engine and the transmission during both the operationand storage of the helicopter. Because the engine compartment isgenerally oriented above the cabin section, any leaking fluidseventually seep or drip into the cabin section unless proper sealingmechanisms are in place. The inflow of these leaking fluids can spoil,stain, or damage the cabin's interior materials, such as, seat coversand acoustic linings. In addition, the leaking fluids can severelydamage or destroy sensitive electronic equipment that may be placed inthe cabin section of a helicopter.

During routine inspection and maintenance it is necessary to have bothready visual and physical access to portions of the engine or at leastthe rotor transmission. Such access is required to check critical fluidlevels; to replace worn, damaged or depleted parts or filters; or toadjust mechanical systems. Typically, various access panels in or aroundthe engine or transmission compartments provide the requisite openingsto achieve ready access to the engine and the rotor transmission. Insome helicopters, a forged or fixed airframe structure forms an accessopening that is located below the rotor transmission housing and abovethe cabin section. The opening is thus accessible through the cabin'sceiling. This access opening, however, must be sealed by a cover againstthe inevitable oil and fluid drippings which the engine and the rotortransmission will produce, as well as against water leakage into thecabin.

The access opening below the engine compartment in the helicopters, suchas the “M” model BLACKHAWK® helicopter, made for the United States bySikorsky Aircraft Company of Stratford, Conn., is defined by both theaircraft structural forgings and a flexible or yieldabledownwardly-turned skirt which is riveted onto the helicopter's forgedstructure. The skirt is thin and many times more flexible relative tothe helicopter's forged structure.

Prior cover designs included a covering plate that is attached directlyto the flexible skirt with a hollow seal sandwiched therebetween. Onehollow seal used in prior designs resembled the flexible, hollow doorseals used around car doors or refrigerator doors. However, the skirtcontains surface aberrations, such as, the protruding rivet heads fromthe rivets that secure the skirt to the forged helicopter structure.When the seal engages both the skirt and the rivet heads, it may bedisplaced or deformed enough to create gaps between the seal and theskirt. Leakage of fluids past the seal may then occur. Accordingly, thehollow seal traversing these aberrations, though sandwiched between theskirt and the covering plate, is generally unable to provide a suitable,consistent, long-term fluid seal. Moreover, flexing of the flexibleskirt during operation of the helicopter could, in addition oralternatively to gapping described above, also cause the seal to gapthereby allowing fluid leakage. Drip pan structures disclosed in U.S.Pat. Nos. 6,112,856; 6,216,823; 6,446,907; and Design Pat. No. D444,443,which are fully incorporated herein by this express reference, provideimprovements and solutions to the aforementioned difficulties.

The “M” model is being produced by Sikorsky and is in service with theU.S. military, for example, in Afghanistan. In the “M” model, and inother aircraft with what are or will be similarly-shaped skirts, theaccess opening has at least one corner of the skirt pulled outwardly toallow direct and straight-through access to the filter, alleviating theneed to tilt or otherwise reorient a filter for removal and/orinstallation in prior model BLACKHAWK® helicopters. However, theaforementioned structures are not readily adaptable for use with the “M”Model BLACKHAWK® helicopter due to a change in configuration of theskirt. In this regard, an improved drip pan apparatus for such a skirtconfiguration, such as that disclosed in U.S. Publication No.2009/0159739, which is incorporated herein in its entirety, addressesthe problems created by the “M” model skirt configuration.

In addition to shielding the cabin from fluid, the geometry of the panstructures cannot protrude significantly into the interior of the cabinsection. Any protrusion from the ceiling that further reduces theavailable head room of the cabin section is undesirable and may beprohibited by regulation. For example, regulations may prohibitprotrusions which decrease the available “head room” for a person of aspecific height or taller. In addition, because weight is critical tothe operation of any aircraft, heavy cover constructions areundesirable.

However, in addition the aforementioned problems and limitations, otherproblems and limitations have been identified with the “M” model. Inthis regard and by way of example, FIG. 1 shows a configuration of atypical BLACKHAWK® helicopter 10, for example, a “M” Model BLACKHAWK®helicopter. In the configuration shown, the helicopter 10 has a cabin 12(dashed outline) in which passengers, equipment, and cargo may rideduring flight. Located just above the cabin 12 is at least one engine 14which powers to a rotor transmission 16. The rotor transmission 16 isoperatively connected to a shaft 18 which imparts rotary motion to themain rotor 20. The rotor transmission 16 is also operatively connectedvia a drive shaft (not shown) to a tail rotor 22.

The rotor transmission 16 requires frequent inspection and maintenanceto ensure its proper operation. To facilitate easy and ready access tothe rotor transmission 16, one or more rotor transmission accessopenings may be provided on both the exterior and interior of thehelicopter. For example, a transmission access opening 205 may belocated within the cabin 12 to provide the requisite access to the rotortransmission 16 that is situated directly above the cabin 12. The accessopening 205 generally has some type of removable cover, to separate thetransmission 16 from the cabin area 12.

As shown in FIG. 2A, to accommodate attachment of such a removablecover, a flexible skirt 207 may be secured to an airframe member 206around the periphery of opening 205 by rivets 28. Skirt 207 may be manytimes more flexible than the access opening 205 as is defined by theairframe member 206, to which it is attached. To prevent leakage offluid into the cabin 12, a pan structure, for example, a drip panapparatus 200 shown in FIGS. 2A, 2B, 3A, and 3B may be used to cover andseal the access opening 205.

The cabin 12 is more fully illustrated in FIG. 3A. The helicopter 10 maybe equipped to transport personnel or equipment generally or may beequipped for a specific mission or to perform a specific function. Byway of example, the interior of the cabin 12 may be outfitted with theequipment necessary to insert and/or extract soldiers from thebattlefield. In this regard, a Fast-Rope Insertion and Extraction System(FRIES) 30 may be installed to the ceiling of the cabin 12 below thetransmission 16.

The FRIES 30 generally includes a main tube or bar 32 that may besecured to the airframe member 206 (shown in FIG. 2A) with barrel nuts(not shown) or the like on both sides of the access opening 205. The bar32 generally spans the access opening 205 and is positioned directlybelow the drip pan apparatus 200. The FRIES 30 may include one or moreextendable/retractable or telescoping locking mount bars 34 thatslidably engaged the bar 32. The telescoping bars 34 may be selectivelyextendable to project from the cabin 12. In operation, once the bar 34is extended, one or more rappelling ropes or a cable (not shown) maydangle from one of the bars 34. In this extended configuration,personnel may rappel from the helicopter 10 or be extracted from a lowersurface while the helicopter 10 remains aloft.

As shown in FIG. 3A, attachment of the FRIES 30 to the ceiling of thecabin 12 leaves little, if any, clearance between the drip pan apparatus200 and the bars 32, 34. As is described in more detail below, the lackof clearance between the bars 32, 34 and the drip pan apparatus 200creates problems with the inspection and maintenance of the transmission16 via access opening 205 and restricts the configuration, including thedimensions, of the drip pan apparatus 200. By way of example, the FRIES30 may be spaced from the drip pan apparatus 200 by at most about 2inches, and by way of additional example may be spaced from the drip panapparatus 200 from about one-half inch to about 2 inches. It will beappreciated that other bar configurations may be secured to the airframe206, span the access opening 205, and may be used to support a winch orother device for lowering and/or lifting personnel, weapons, or otherequipment to or from the cabin from below the helicopter 10.Furthermore, other equipment, for example, troop seat bars (not shown),may be supported by other bar configurations secured to the ceiling ofthe helicopter in the same or similar position as the FRIES 30 andimpede access to the transmission 16 and, in some instances, blockaccess to the tabs 202 (described below) along one or more sides of theapparatus 200.

By way of additional example and with reference FIG. 3B, the helicopter10 may be equipped as a MedEvac. In this regard, a medevac bar 40 ratherthan the FRIES 30, described above, may be secured to the ceiling of thecabin 12. Typically, similar to the bars 32, 34, the medevac bar 40 isattached to the airframe member 206 on each side of the access opening205 such that the bar 40 spans across the access opening 205. As such,the medevac bar 40 is directly below the drip pan apparatus 200.However, unlike the FRIES bar 32, 34, the medevac bar 40 generallydefines a top rotation point of a rotatable partition 42 that partiallydivides the cabin 12 and that supports one or more litters or stretchers44. The partition 42 may be selectively positionable about an axis 46.Stretchers may be loaded onto the partition 42 and the partition 42 maythen be rotated 90 degrees prior to helicopter liftoff

When the helicopter 10 is so equipped, the medevac bar 40 is spaced fromthe drip pan apparatus 200. The clearance between the drip pan apparatus200 at any particular location and the medevac bar 40 may be less thanthat of the FRIES bars 32, 34. For example, the clearance between themedevac bar 40 and the drip pan apparatus 200 may be on the order of afew thousandths of an inch and may be roughly equivalent to thethickness of a sheet of paper (e.g., 0.002 to 0.006 inches).

In each of these exemplarily equipped helicopters, the mission specificequipment is positioned immediately or directly below the drip panstructure. The position of the equipment and the necessity that it besecurely fastened to the frame member 206 complicates access through theaccess opening 205. As a result, inspection and maintenance of thetransmission 16 from within the cabin 12, which may only be accessiblevia the access opening 205, is made troublesome or nearly impossible bythe mission specific equipment. Generally, the mission specificequipment may span the access opening 205 or otherwise partially blockor interfere with access to the transmission 16 through the accessopening 205, as is exemplified by the Medevac or FRIES bar, above. Inspite of this interference or blockage, the configuration of the drippan structure must allow for attachment of mission critical equipment onthe one hand, but allow for inspection of the transmission 16 and, whennecessary, removal of the pan structure or at least a portion thereofwithout removal of the mission critical equipment on the other hand.

For instance, the FRIES 30 (FIG. 3A) or the medevac bar 40 (FIG. 3B)interferes with the inspection and maintenance of the transmission 16via the access opening 205. However, removal of either one to gain fullaccess through the access opening 205 may require initial removal ofother equipment, for example, the associated rotatable partition 42 inthe case of the medevac bar 40. Similarly, removal of the FRIES 30 thatspans the access opening 205 is not only difficult or impossible withoutdamaging that or other equipment or helicopter 10, but it is also timeconsuming. Thus, full access through the access opening 205, whiledesirable, is often not economically nor logistically feasible once thehelicopter 10 is outfitted for a specific mission or purpose. Althoughspecific mission equipment (e.g., the FRIES 30 and medevac bar 40) aredescribed above, it will be appreciated that other similar systems maybe installed to the ceiling in the cabin 12 to provide similar oralternative functions for a specific mission or operation.

In addition to the space constraints imposed by mission specificequipment or possibly due to the space constraints, applicant recognizedanother issue with the BLACKHAWK® “M” model helicopter. In particular,the “M” model fails to provide sufficient clearance between thetransmission and the prior drip pans and/or within the cabin between thecabin floor and prior pans. That is, one or both of these dimensions maybe insufficient. As is described in more detail below in conjunctionwith FIGS. 4 and 5, there is a wire bundle that passes between thetransmission and prior pan. It was recognized that the wire bundle forthe “M” model is larger than previous models, and that the distancebetween the transmission and prior pans would not adequately accommodatethe relative increase in size. A solution to which is exacerbated by thespacial constraints set forth above. Accordingly, simply moving the panstructure away from the transmission may not be a solution and may causeadditional problems.

Accordingly, it is one objective to provide an improved leak-proof drippan structure for use in BLACKHAWK® helicopters.

Another objective is to provide an improved drip pan structure that willallow inspection of an engine or transmission compartment from a cabinsection of a helicopter without first removing mission specificequipment from the cabin section thereof.

Another objective is to provide an improved drip pan structure that willeffectively and consistently seal fluid from passage from an engine ortransmission compartment to a cabin section of a BLACKHAWK® “M” modelhelicopter and similar airframes.

Another objective is to provide an improved drip pan structure whichpermits quick visual and physical access to the engine or transmissioncompartment of a BLACKHAWK® “M” model helicopter and similar helicopterswithout requiring modification to the existing aircraft structure.

Still another object of this invention is to provide a drip panstructure that can be attached to the existing structure of a BLACKHAWK®“M” model helicopter while both improving the headroom available in thecabin and providing clearance to other existing components, including awire bundle, proximate the transmission.

SUMMARY OF THE INVENTION

To these and other ends, in one embodiment, there is a drip pan forcooperation with a frame for covering an access opening to a rotortransmission of a helicopter. The frame has a seal surface. The drip panincludes a substantially planar member of a fiber-reinforced compositeand has a seal surface that is configured to cooperate with a sealmember disposed between the substantially planar member and the frame toform a fluid-tight seal between the seal surface of the substantiallyplanar member and the seal surface of the frame to seal the accessopening from fluid leakage. In one embodiment, the fiber-reinforcedcomposite is a carbon fiber-reinforced composite.

In one embodiment, there is a drip pan apparatus for a helicopter havingan airframe member defining an access opening. A skirt is secured to theairframe member around the periphery of the access opening. The drip panapparatus includes a frame of a fiber-reinforced composite and aninwardly-facing peripheral surface. The frame is adapted to be securedto the skirt. A drip pan of a fiber-reinforced composite defines anaccess port and has an outwardly-facing peripheral surface that isconfigured to cooperate with the inwardly-facing peripheral surface ofthe frame. At least one of the inwardly-facing peripheral surface andthe outwardly-facing peripheral surface is a machined surface. A sealmember is configured to be disposed between the inwardly-facingperipheral surface and the outwardly-facing peripheral surface andconfigured to form a fluid-tight seal between the drip pan and theframe.

In one embodiment, there is a drip pan apparatus for use with ahelicopter having a cabin section, a rotor transmission oriented atleast in part above the cabin section, a rotor transmission accessopening defined by an airframe member of the helicopter in the ceilingof the cabin section, a skirt secured to the airframe member around theperiphery of the access opening, and a wire bundle between the rotortransmission and the cabin section. The drip pan apparatus includes aframe adapted to be attached to the skirt. The frame has aninwardly-facing peripheral surface. A drip pan is configured tocooperate with the frame and has an outwardly-facing peripheral surface.A seal member is disposed between the outwardly-facing peripheralsurface and the inwardly-facing peripheral surface. At least one of theframe and the drip pan has a discontinuous edge structure configured toface the transmission and to accommodate the wire bundle proximate theframe and/or the pan when the frame is attached to the helicopter andthe drip pan is removably secured to the frame.

In one embodiment, there is a method of removing a drip pan from ahelicopter having a cabin section, a rotor transmission oriented atleast in part above the cabin section, a rotor transmission accessopening in the ceiling of the cabin section, special operationsequipment spanning the access opening, and a drip pan apparatus coveringand sealing the access opening. The drip pan apparatus has a drip pandetachably secured to a frame. The drip pan includes a first drain linecoupled to a first drain tube that is attached to the helicopter at afirst location. A drain port assembly is detachably secured to the drippan and includes a second drain line coupled to a second drain tube thatis attached to the helicopter at a second location different from thefirst location. The special operations equipment is positioned betweenthe first drain line and the second drain line. Movement of the drip panto remove the drip pan from the frame causes the special operationsequipment to interfere with one of the first or second drain lines. Themethod includes detaching the drain port assembly from the drip pan toexpose an access port. The drain port assembly remains coupled to thesecond drain tube and attached to the helicopter at the second location.The method further includes releasing the drip pan from the frame andsliding the drip pan in a direction that moves the access port betweenthe special operations equipment and the rotor transmission to removethe drip pan from the frame. Once removed, a technician may access therotor transmission through the opening.

In one embodiment, there is a method of making a drip pan apparatus fora helicopter having an airframe member defining an access opening. Thehelicopter includes a skirt secured to the airframe member around theperiphery of the access opening. The method includes placing a pluralityof sheets of an uncured fiber-reinforced composite material on oneanother to form an uncured stack. The uncured stack is then cured. Themethod further includes cutting a frame and a drip pan from the curedstack. Cutting the frame forms an inwardly-facing peripheral surface,and cutting the drip pan forms an outwardly-facing peripheral surface.The inwardly-facing peripheral surface and the outwardly-facingperipheral surface are each configured to sealingly engage a seal memberand form a fluid-tight seal therebetween.

The above and other objectives and advantages of the present inventionshall be made apparent from the accompanying drawings and thedescription thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate an embodiment of the inventionand, together with the general description of the invention given aboveand the detailed description of embodiments given below, serve toexplain the principles of the present invention.

FIG. 1 is a side elevation view of a helicopter according to oneembodiment of the invention;

FIG. 2A is an exploded isometric view of components of a drip panapparatus partially described in U.S. Publication No. 2009/0159739 (the'739 publication);

FIG. 2B is a plan view of components of the drip pan apparatus shown inFIG. 2A when viewed from the cabin of the helicopter;

FIG. 3A is a side elevation view of the cabin section of a helicopterequipped with a FRIES;

FIG. 3B is a side elevation view of the cabin section of a helicopterequipped as a medevac;

FIG. 4 is a cross-sectional view of a drip pan apparatus taken alongsection line 4-4 in FIG. 3B;

FIG. 5 is a cross-sectional view of a configuration of a prior drip panstructure taken along section line representative of section line 4-4 inFIG. 3B;

FIG. 6 is a top plan view of one embodiment of a drip pan apparatus whenviewed from the transmission of the helicopter with a FRIES and amedevac bar shown in phantom line;

FIG. 6A is an enlarged view of the encircled area 6A of FIG. 6;

FIG. 7A is a cross-sectional view of one embodiment of a drip panapparatus taken along a section line 7A-7A of FIG. 6;

FIG. 7B is a cross-sectional view of one embodiment of a drip panapparatus taken along a section line 7A-7A of FIG. 6;

FIG. 8 is an exploded isometric view of a drip pan apparatus accordingto another embodiment of the invention;

FIG. 8A is a cross-sectional view of the drip pan apparatus of FIG. 8taken along section line 8A-8A;

FIG. 8B is an enlarged view of the encircled area 8B of FIG. 8Adepicting one embodiment of the drip pan apparatus of FIG. 8A;

FIG. 8C is an enlarged view of the encircled area 8B of FIG. 8Adepicting an alternative embodiment of the drip pan apparatus of FIG.8A;

FIG. 9 is a cross-sectional view of one embodiment of the inventiontaken along a section line representative of the section line 7A-7A ofFIG. 6 of the embodiment of the drip pan apparatus depicted in FIG. 8;

FIGS. 10A-10D illustrate a sequence of stacking sheets of afiber-reinforced composite to form one or more of a drip pan, a frame, aport cover, and a drain port assembly according to one aspect of theinvention;

FIGS. 11A-11D illustrate a sequence of stacking sheets of afiber-reinforced composite to form a drip pan apparatus according to oneaspect of the invention;

FIGS. 12A-12F illustrate a sequence of machining a drip pan apparatusfrom a single stack of sheets of fiber-reinforced composite according toone aspect of the invention;

FIG. 13 is bottom plan view of one embodiment of a removable drain portassembly according to another aspect of the invention;

FIG. 14 is a cross-sectional view of a portion of the removable drainport assembly taken along section line 14-14 of FIG. 13;

FIG. 15 is a bottom partially-cut-away plan view of one embodiment of adrain grate according to another aspect of the invention;

FIG. 16 is a bottom plan view of another embodiment of a removable drainport assembly;

FIG. 17 is a cross-sectional view taken along section line 17-17 of theremovable drain port assembly shown in FIG. 16; and

FIGS. 18, 19, and 20 are each cross-sectional views of exemplaryembodiments of a bracket according to another aspect of the invention.

DETAILED DESCRIPTION OF INVENTION

To those ends, embodiments of the present invention address the minimalclearance between mission specific equipment while sealing the accessopening 205 from fluid leakage. Additionally, these embodiments alsoaddress or allow access through the access opening 205 of the helicopterwithout removal of the mission specific equipment. However, in additionto the challenges posed by limited space available between missionspecific equipment secured to the ceiling of the cabin 12 and, forexample, the drip pan apparatus 200, as briefly set out above, there isanother problem with the “M” model BLACKHAWK® helicopter.

With reference now to FIG. 4, it is known that a wire bundle 26 passesbetween the apparatus 200 and the transmission 16. The wire bundle 26contains a plurality of individual wires that carry electrical signalsor electrical power between different components of the helicopter 10.Applicant recognized that the wire bundle 26 may contact portions of thedrip pan apparatus 200 and/or may also contact the transmission 16 andthat it is the combination of these components, including the size ofthe wire bundle 26 relative to prior wire bundles, that may causecontact of the wire bundle 26 with the transmission 16 and the drip panapparatus 200. In some configurations, it is thought that the wirebundle 26 may actually be forcibly sandwiched between a portion of thepan structure and the transmission 16. By way of example and withreference to FIG. 4, installation of the drip pan apparatus 200 over theaccess opening 205 may force the wire bundle 26 into contact with thetransmission 16 or otherwise pinch the wire bundle 26 between the two.

One illustrative pinch point that may occur is indicated by the arrows36 in FIG. 4. It will be appreciated that the illustrated point ismerely an exemplary contact region between the wire bundle 26 and thetransmission 16 and there may be other locations at which the wirebundle 26 contacts both the transmission 16 and the adjacent panstructure. Contact between the wire bundle 26 and another component,e.g., the drip pan apparatus 200 and/or the transmission 16, is notdesirable. Although the contact force may be minimal, the long termresult of this configuration may be detrimental to the operation of thehelicopter 10.

In this regard, and by way of example, there are at least two problemsthat may be associated with pinching the wire bundle 26 between the drippan apparatus 200 and the transmission 16. One problem is that one ormore of the individual wires in the bundle 26 may be chafed due to thenormal vibration of the helicopter 10 that causes relative movement atthe contact or pinched location. If sufficiently chafed, the metal ofthe wire may become exposed and electrical problems, such as, electricalshorts, may result.

While wire chafing may be a source of electrical problems, the other,and vastly more costly problem, is that the transmission 16 may also bechafed or be worn by the wire bundle 26. In addition, or alternatively,as is known, transmissions are sensitive to foreign material, forexample, the debris produced by wire chafing or as an indirect resultthereof. Introduction of foreign material or direct wear of transmission16 may cause a reduction in serviceable life of the transmission 16 oroutright mechanical failure thereof. It will be appreciated that theseproblems are exemplary only and other problems may be the direct orindirect result of pinching the wire bundle 26 between the drip panapparatus 200 and the transmission 16. While various embodiments of drippans are shown and described herein with reference to the BLACKHAWK®Model “M” helicopter, it will be appreciated that these embodiments mayfind use in numerous other helicopter makes and models.

With reference to FIG. 5, there is shown a prior pan structure at 27. Asshown, the pan structure 27 provides clearance between the missioncritical equipment, e.g., the medevac bar 40 (as shown in phantom line).However, the additional clearance is achieved at the expense ofcompressing the wire bundle 26 against the transmission 16. Thiscompression may extend over the length of the wire bundle 26, as shownby the arrows 38. The configuration of the pan structure 27 fails torecognize compression or pinching of the wire bundle 26 against thetransmission 16 as a problem. As set forth above, there may be direct,negative consequences to such a configuration. In addition, this priorart structure also relies on a sandwich type seal. Thus, in addition tofailing to recognize pinching of the wire bundle 26, this configurationmay not be resistant to fluid leakage during operation of a helicopterso equipped.

To address these and other issues, and with reference to FIGS. 6 and 7Ain which like reference numerals refer to like portions of FIG. 2A, animproved drip pan apparatus 300 includes a frame 315, a pan 320, and aseal member, such as o-ring 222. In use, the frame 315 is secured toskirt 207 (shown in FIG. 7A) and has an inwardly-facing peripheralsurface 335. The pan 320 has an outwardly-facing peripheral surface 339which is spaced from the inwardly-facing peripheral surface 335. Theseal member 222 contacts each of surfaces 335 and 339 to prevent fluidleakage between the pan 320 and frame 315.

As shown in FIG. 6, in one embodiment, the drip pan 320 defines one ormore access ports 223-226 and a filter access port 228, which isprovided with a removable port cover 229 having a view window 236. Oncethe drip pan 320 is secured to the frame 315, the status of a filter orother component in or on the transmission 16 (shown in FIG. 7A) may beviewed through the view window 236. Any one or more of the access covers70 may be removed from its respective access port 223-226 such thatroutine maintenance and inspection of components within access opening205 may be performed.

The drip pan 320 is inserted into the frame 315 in the positionillustrated in FIGS. 6 and 7A, where seal member 222 creates aperipheral seal between the drip pan 320 and frame 315 and providescontinuous sealing during airframe flexure and without the disadvantageof any face seal in this regard. Once the pan 320 is inserted into theframe 315, a drain line 104 may be connected to pass fluids from drain100. However, according to one embodiment of the invention, the drip panapparatus 300 may include one or more other drains as set forth in moredetail below. The pan 320 may be secured in sealing engagement with theframe 315 by operation of a plurality of resilient members 50 as isshown in FIG. 2A. Each resilient member 50 having elongated arms 52 withcurved portions 54. Resilient members 50 are free to pivot aboutbrackets 58. Curved portions 54 selectively engage slots 56 openingtoward and located about the interior periphery of frame 315.

The drip pan apparatus 300 may differ from that pan apparatus of the'739 publication in the area 6A shown in FIG. 6. As set forth above, thepan structure 27 does pinch and the drip pan apparatus 200 may pinch orotherwise push the wire bundle 26 into contact with the transmission 16.In one embodiment, the drip pan apparatus 300 includes a discontinuousedge structure that accommodates the wire bundle 26 proximate theretosuch that the wire bundle 26 may not detrimentally contact the drip panapparatus 300. By way of example, the discontinuous edge structure mayinclude a rib along the peripheral edge of the pan 320 that isinterrupted by a groove. The groove may provide a relief area for thewire bundle 26. The discontinuous edge structure, however, may notcompromise the structural integrity of the drip pan apparatus.

By way of further example, in one embodiment of the invention and withreference to FIGS. 6, 6A, and 7A, a recess 322 may be formed in theframe 315. Unexpectedly, such a recess 322 may not compromise thestructural integrity or sealability of the frame 315. The recess 322 maydefine an inner rim 318 that is comparatively further from thetransmission 16 and that may result in a thickness T₁ of the frame 315along the recess 322 that is less than at an inner rim 218 adjacent therecess 322 and labeled T₂. Furthermore, the recess 322 may extend over alimited length L along a rail 247 a without comprising the structuralintegrity of the drip pan apparatus 300. It will be appreciated thatalthough the recess 322 is shown as a flat surface that is generallyparallel to, for example, an elongated recess 110, the configuration ofthe recess 322 is not so limited. Other configurations may include ataper or chamfer along a limited portion or along the entire length ofthe rail 247 a in this region. Furthermore, while shown, it is notnecessary that the recess 322 expose a portion of the outwardly-facingperipheral surface 339 of the pan 320. In this regard, the thickness T₁may be greater than that shown such that the surface 339 remains coveredby the inner rim 318.

In addition or as an alternative to the recess 322, and with continuedreference to FIGS. 6, 6A, and 7A, the pan 320 may include a recessedportion 324 along the periphery thereof and may substantially align withthe recess 322. By way of example only, the recessed portion 324 mayinclude a tapered surface 326 that extends from a pan base surface 328to the periphery of the pan 320 at or near the outwardly-facingperipheral surface 339. As such, the pan 320 may be thinner at or inregions near the outwardly-facing peripheral surface 339 in area 6A ofFIG. 6 than in regions proximate the recess 322.

It will be appreciated that while both the recess 322 and recessedportion 324 are collectively shown and described in the frame 315 andpan 320 in FIGS. 6, 6A, and 7A, the pan 220 shown in FIG. 2 may besecured to the frame 315. Similarly, the exemplary pan 320 havingrecessed portion 324 shown in FIG. 6 may be secured to the frame 215shown in FIG. 2. In other words, it may be sufficient to alleviatepinching or provide clearance for the wire bundle 26 by use one of theframe 315 or the pan 320 or both the frame 315 and the pan 320 as eithermay provide additional clearance for the wire bundle 26. It will also beappreciated that this may be accomplished without moving (i.e.,lowering) either of the frame 315 or the pan 320 toward the missioncritical equipment, e.g., the medevac bar 40, and without causing theframe 315 or the pan 320 to protrude into the cabin 12.

In this regard, the improvement in the clearance between the drip panapparatus 300 and the transmission 16, while measured in thousandths ofan inch or fractions thereof, may be sufficient to avoid contact withthe wire bundle 26 when the drip pan apparatus 300 is installed andduring operation of the helicopter 10. By way of example, theimprovement in clearance between the transmission 16 and the drip panapparatus 300 may be measured perpendicular to the airframe member 206to a plane that includes the inner rim 318 of the frame 315. In theexemplary configuration shown in FIG. 7A, the recess 322 may increaseclearance by between about 0.0500 of an inch and 0.1500 of an inch, andby way of further example, by between about 0.0800 of an inch and 0.1400of an inch. By comparison of the drip pan apparatus 200 of FIG. 4 withFIG. 7A, there may be an improvement in clearance or space between thewire bundle 26 and the frame 315. By comparison of the prior pan 27 ofFIG. 5 with FIG. 7A, the interference fit shown in FIG. 5 may beeliminated.

In one embodiment and with reference to FIG. 7B, a drip pan apparatus400 may include a frame 415, a pan 420, and the seal member 222. Incomparison with the drip pan apparatus 300 shown in FIG. 7A, the frame415 may be narrower in width W₁₃ along the length L shown in location 6Aof FIG. 6 when compared to the width W₁₂ of the frame 315 shown in FIG.7A and/or narrow in width when compared to the width W₅ shown in FIG.2B. Accordingly, the location of the inwardly-facing peripheral surface435 and the outwardly-facing peripheral surface 439 may be moved towardthe skirt 207 as indicated by the arrow 440 in FIG. 7B as compared tothe location of the inwardly- and outwardly-facing surfaces 335, 339relative to the skirt 207 shown in FIG. 7A. Thus, the inner rim 318shown in FIG. 7B is moved toward the skirt 207 and, consequently, awayfrom the wire bundle 26 and transmission 16.

Further in this regard and with reference to FIGS. 2B, 7A, and 7B, thewidth W₁₃ may represent the width of a rail 447 a along the entirelength thereof. Thus, the width W₁₃ may be less than the width W₅ ofrail 247 a labeled in FIG. 2B or less than width W₁₂ as labeled in FIG.7A. It will be appreciated that the remaining widths of rails 247 b, 247c, and 247 d (shown in FIG. 2B) may be unchanged such that overall thepan 420 is larger than pan 320 or pan 220. Alternatively, by way ofexample, the dimensions of the pan 420, 320, and 220 may be comparable,but the widths of the rails 247 b, 247 c, 247 d may be adjusted toaccount for width W₁₃ such that any of pans 320, 220 may be sealinglyengaged with the frame 415. As such, it will be appreciated that whilethe frame 415 and pan 420 are shown together in FIG. 7B, embodiments ofthe present invention are not so limited, as the frame 415 may sealinglyengage with the pan 220 (FIGS. 2A and 2B) or the pan 320 (FIG. 6). Inaddition to movement of the surfaces 435 and 439 toward the skirt 207 ascompared to surfaces 335, 339, the frame 415 and/or the pan 420 mayinclude recess 322 or recessed portion 324, as set forth above. As such,one or both of the recess 322 and recessed portion 324 may be used incombination with the width W₁₃ of rail 447 a, i.e., the position of thesurfaces 435, 439 relative to the skirt 207 to improve clearance betweenthe transmission 16 and the nearest surface of the drip pan apparatus400.

In one embodiment and with reference to FIG. 8 in which like referencenumerals refer to like portions shown in FIGS. 2A and 2B, a drip panapparatus 500 may include a frame 515, a pan 520, and the seal member222. The drip pan apparatus 500 is adapted to cover and seal accessopening 205 of the helicopter 10 and thereby prevent fluid drippingsfrom engine 14, transmission 16, or other fluids from passing throughaccess opening 205.

To that end and with reference to FIGS. 8, 8A, and 8B, the frame 515 maybe generally planar having tabs 502 for attachment to the skirt 207. Theframe 515 has an inwardly-facing peripheral surface 535 to which theseal member 222 engages during use of the apparatus 500. While theinwardly-facing peripheral surface 535 is shown as a substantially flatsurface, it will be appreciated that the frame 515 is not limitedthereto as there are other configurations which may be used for engagingthe seal member 222.

With continued reference to FIGS. 8 and 8A, the pan 520 may also besubstantially planar. That is, pan 520 may be defined predominately by aplane of uniform thickness, though the pan 520 may have features thatprotrude above and/or below an otherwise uniform plane. The pan 520 hasan outwardly-facing peripheral surface 539. Additionally, the drip pan520 may define a plurality of access ports 223-226 and a filter accessport 228, as described above. Any one or more of the access covers 70may be removed from its respective access port 223-226 such that routinemaintenance and inspection of the transmission 16 or other componentswithin access opening 205 may be performed.

In one embodiment and with reference to FIGS. 8A-8C, the pan 520includes an outer or bottom flange 540 that may radially extend beyondthe outwardly-facing peripheral surface 539 of a core member 542. Thebottom flange 540 may be secured to the core member 542 on the cabinside thereof As such, the flange 540 may function as a stop duringinsertion of the pan 520 into frame 515. Also shown, in one embodiment,the pan 520 may include a top flange 544 that may also extend radiallybeyond the surface 539 and may oppose the bottom flange 540. As with thebottom flange 540, the top flange 544 may be secured to core member 542though embodiments of the invention are not limited thereto. Forexample, top flange 544 may be secured to the frame 515 and extendradially inward over inwardly-facing surface 535. Together, as shownbest in FIG. 8B, the bottom and top flanges 540, 544 may define a recess546 therebetween. The recess 546 may be configured to receive sealmember 222. One or both of the bottom and top flanges 540, 544 mayretain the seal member 222 in contact with the surface 539 by limitingor restricting sliding movement of the member 222 along the surface 539during installation, use, or removal of the pan 515 from the frame 520.

In addition, in one embodiment, an o-ring stop 548 may also definerecess 546. In particular, the o-ring stop 548 may be positioned indirect contact with the bottom flange 540. The o-ring stop 548 may beadhesively secured to both the core member 542 and the bottom flange540. Consequently, when the pan 520 is inserted into the frame 515 andthe bottom flange 540 abuts the frame 515, the o-ring stop 548 may carryor spread any load generated by the contact of the flange 540 with theframe 515 over a larger area provided by the stop 548. The stop 548 maythus help resist bending or peeling off of the flange 540 duringinstallation of the pan 520. In one embodiment, a lubricant may be usedon the seal member 222 and/or on surfaces 535 and/or 539 to install thepan 520 in the frame 515.

In an alternative embodiment and with reference to FIG. 8C, in lieu ofthe top flange 544, the outwardly-facing peripheral surface 539 maydefine the recess 546. However, by this configuration, the recess 546may perform substantially the same as the configuration shown in FIG. 8Bthough, as is described in detail below, the method of making theexemplary configurations may differ.

With reference to FIGS. 8 and 8A, in one embodiment, the drip panapparatus 500 may further include a drain 530 which functions in asimilar manner as the drain 100 of FIG. 2A and described in the '739publication. Once the pan 520 is installed into the frame 515, a draintube 106 (shown in FIG. 3B) may be connected to pass fluids from drain530 to a location outside of the cabin 12.

Similar to embodiments described above and with reference to FIGS. 8 and9, the frame 515 cooperates with the skirt 207 to cover access opening205. And, once the frame 515 is installed on the skirt 207 and the pan520 is inserted into frame 515, the apparatus 500 prevents fluiddrippings from entering the cabin 12 of the helicopter 10. In thisrespect, the outwardly-facing peripheral surface 539 may be spaced fromthe inwardly-facing peripheral surface 535 by the seal member 222 whenthe pan 520 is installed in the frame 515. The seal member 222 forms afluid-tight seal with both the frame 515 and the pan 520.

To that end and with reference to FIG. 9, fasteners 201 may secure theframe 515 to the skirt 207 through tabs 502. In one embodiment, a washer504 may be positioned between the frame 515 and the skirt 207, andfasteners 201 may pass through each to secure the frame 515 to the skirt207. A flexible sealing media (not shown), such as PROSEAL™(manufactured by PRC Desoto International, Inc. of Indianapolis, Ind., aPPG Company) or other sealant may be used to seal the frame 515 to skirt207. Accordingly, during installation, a bead of the flexible sealingmedia may be placed on the J-shaped rim of the skirt 207 and the frame515 may then be pushed thereon to squeeze the flexible sealing mediabetween the skirt 207 and frame 515. The flexible sealing media may bedisplaced to one or both sides of the skirt 207 and in contact with theframe 515. Alternatively or in addition to the above-described location,the flexible sealing media may be applied between the skirt 207 and theframe 515 at other locations. However, it will be appreciated thatembodiments of the present invention are not limited to the particularlocation of any sealant between the frame 515 and the skirt 207.Thereafter, drip pan 520 is inserted into the frame 515 where sealmember 222 creates a peripheral seal between the drip pan 520 and frame515 and provides continuous sealing during airframe flexure and withoutthe disadvantage of a face seal.

In one embodiment and with reference to FIG. 8, the frame 515 may haveclips 522 defining slots 524 when attached to the frame 515. Attachmentmembers 50 similar to those disclosed in the '739 publication releasablysecure the drip pan 520 to the frame 515. Elongated arms 52 with curvedportions 54 selectively engage the clips 522 via slots 524. In oneembodiment, the clips 522 are located at or flush with theinwardly-facing peripheral surface 535 or less than about 0.25 of aninch measured perpendicularly therefrom. By this configuration, thecurved portions 54 are captured by the clips 522 at a location that iscloser to the junction between the outwardly-facing peripheral surface539 and the inwardly-facing peripheral surface 535. Thus, the positionof the clips 522 relative to the junction of the surfaces 535, 539limits the flexibility or reduces relative movement between the frame515 and the drip pan 520. Further in this regard, the clips 522 may beconfigured to resiliently deflect or bend as they are inserted intoslots 524. By way of example, the clip 522 may be tapered to define arelatively large opening though the slot 524 may narrow in a directionaway from the pan 520. As such, the curved portion 54 may be easilyinserted into slot 524. However, upon further insertion of the curvedportion 54, the arm 52 may bend, bow, or deflect as a result of thetapered clip 522 thereby increasing the force of contact between atleast the clip 522 and the curved portion 54. It will be appreciatedthat an increase in force may translate into an increase in frictionbetween the two components thus requiring a greater force for withdrawalof the curved portion 54 therefrom and may result in a more rigidarrangement as between the pan 520 and the frame 515.

In one embodiment, the drip pan apparatus 500 may be thinner than thedrip pan apparatus 200, 300, and 400. By way of example and withreference to FIG. 9, the frame 515 may be up to about 50% thinner insimilar locations as frame 315 or frame 415, and by way of additionalexample, may be between 10% and 50% thinner than the frame 215 (shown inFIG. 2A), the frame 315 (shown in FIG. 6), or 415 (shown in FIG. 7B)along the corresponding inner rim thereof. It will be appreciated thatthe frame 515 may be proportionally lighter than any of the frames 215,315, or 415.

Further in this regard, the drip pan 520 may also be thinner than drippans 220, 320, and/or 420. For instance, the relative decrease in thethickness may be up to about 50%, for example, in a central region ofthe drip pan 520 as compared to, for example, drip pan 220 and/or 320.By way of further example, the relative decrease in thickness may be atleast about 10% compared to the drip pans 220 and 320. The weightsavings may be significant. For example, the weight of the pan 520 maybe up to about 50% less than that of the pan 320.

As shown in FIG. 9, as a result of the relative decrease in thickness,the drip pan apparatus 500 may allow the wire bundle 26 to fit withinthe space between the transmission 16 and the drip pan apparatus 500,though the clearance between mission specific equipment remainsunchanged or is improved. In this regard, and by way of example, thedrip pan apparatus 500 may be at most about 0.5000 of an inch thickthrough the thickest portion thereof. However, it will be appreciatedthat the thickest portion thereof may be between about 0.3000 inches andabout 0.4000 inches, or by way of further example between about 0.3200inches and about 0.3800 inches. However, the drip pan apparatus 500 maynot impede or interfere with installation of mission specific equipment,such as the medevac bar 40, the FRIES 30, or a troop seat bar (notshown).

Accordingly, in view of the space constraints, relative positions of thewire bundle 26 and transmission 16, and prevention of the fluid leakageinto the cabin 12, the drip pan apparatus 500 provides for at least thesame clearance or spacing for the mission specific equipment as drip panapparatuses 200, 300, and 400. Furthermore, the drip pan apparatus 500may increase the distance from the apparatus 500 to the transmission 16.Consequently, more room may be provided therebetween such that the wirebundle 26 may not contact the drip pan apparatus 500 which may, in turn,reduce or eliminate chafing of the wire bundle 26 and transmission 16.In this respect, the wire bundle 26 may not be forcibly pinched betweenthe drip pan apparatus 500 and the transmission 16 to a degree wheredetrimental chafing of the bundle 26 and/or the transmission 16 results.In one embodiment, while the apparatus 500 may increase the spaceavailable between the transmission 16 and the pan 520, the apparatus 500provides the same or more headroom in the cabin 12. Thus, pan 520 may bemore easily removed due to more clearance between the apparatus 500 andany special mission equipment.

For example and with reference to FIG. 9, the perpendicular distancefrom the bottom surface of the airframe member 206 at location 60 onwhich the skirt 207 is attached to the plane of the inner rim 526 of theframe 515 may be between about 0.1500 of an inch and about 0.2000 of aninch, and by way of further example the perpendicular distance may bebetween about 0.1700 of an inch and about 0.2000 of an inch. Theperpendicular distance from the bottom surface of airframe member 206 toa plane that includes the top surface of the drip pan 520 at the innerrim 528 of the pan 520 may be between about 0.1000 of an inch and about0.1400 of an inch, and by way of further example, the distance may bebetween about 0.1100 of an inch and about 0.1300 of an inch.

By way of comparison, one embodiment of the drip pan apparatus 500 mayprovide an improvement in distance between the transmission 16 and thedrip pan 520 of at least about 0.1845 of an inch with an increase inclearance being as high as about 0.2000 inches compared to other drippans, for example the drip pan 27 shown in FIG. 5 which compresses thewire bundle 26 against the transmission 16.

With reference again to FIGS. 8 and 8A, in one embodiment, the drip panapparatus 500 is constructed of a fiber-reinforced composite. Thecomposite may include fibers bound in a matrix. It will be appreciatedthat the fibers may be woven in a cloth-like form or be randomlyoriented in mat-like form. The fibers may be made of glass, carbon, orother material that may exhibit greater tensile strength than thematrix. The matrix may be a polymer, such as, an epoxy. However, it willbe appreciated that the composite is not limited thereto as other fibersand polymers are known.

By way of example only, the fiber-reinforced composite may be acarbon-fiber reinforced composite. Accordingly, in one embodiment,portions of the frame 515 and the drip pan 520 may be made fromcarbon-fiber reinforced composite, such as EP258 plain weave carbonfiber-reinforced composite sheet available from Barrday CompositeSolutions of Millbury, Mass. However, non-fiber-reinforced componentsmay be attached thereto. For example, the clips 522, while possiblybeing made of the same carbon fiber-reinforced composite as the frame515 and/or the pan 520, may be made of metal or plastic, which may thenbe secured by adhesive or other means to the drip pan 520. In addition,the access covers 70 may be made of metal, such as aluminum, stainlesssteel, or titanium, or may be made of the same composite material as thepan 520, as is described in more detail below.

In one embodiment, one or both of the frame 515 and the drip pan 520 aremade of a fiber-reinforced composite by a laminating process, describedin detail below. In brief, according to an exemplary laminating process,the frame 515 and/or the drip pan 520 may be constructed by stacking orplacing multiple sheets of the fiber-reinforced composite upon oneanother. The resulting stack may then be cured and machined to form theone or both of the frame 515 and the drip pan 520.

According to an exemplary process and with reference to FIGS. 10A-10D,the frame 515 and/or the drip pan 520 may include a stack 550 containingat least two sheets (individually labeled 552) of the fiber-reinforcedcomposite. It will be appreciated that the number of sheets 552 of thefiber-reinforced composite needed to build up a frame and/or a drip panis determined at least in part by the starting thickness of each sheet552. By way of example, each sheet may be about 0.060 of an inch thickfollowing curing. However, embodiments of the present invention are notlimited to sheets of a particular thickness. Moreover, each sheet 552 inthe stack 550 may be of the same or of a different thickness. Forexample, the frame 515 and/or the drip pan 520 may include from about 2to about 60 sheets of the fiber-reinforced composite, each ofsubstantially equivalent thickness. In one embodiment, the thickness ofthe frame 515 is equal to about 39 or about 40 sheets of carbonfiber-reinforced composite following curing. In one embodiment, the pan520 has a minimum thickness equivalent to about 6 sheets of the carbonfiber-reinforced composite but is at least 40 sheets thick along aboarder or the periphery thereof. For example, the pan 520 may be about39 or about 40 sheets thick within a region of about 2 inches extendingfrom the outwardly-facing peripheral surface 539 toward the center ofthe pan 520. Although not shown, the pan 520 may be uniformly thickthroughout.

As set forth briefly above, the frame 515 and/or the drip pan 520 may bemade by a process that includes stacking sheets 552 of an uncuredfiber-reinforced composite on one another. This uncured composite may bereferred to as “B-stage” material. B-stage composite sheets may behardenable with a subsequent treatment by which the composite becomescapable of bearing loads.

With reference to FIG. 10A, in one embodiment, a base sheet 554 ofB-stage carbon fiber-reinforced composite is placed on a support surface556. Placing of a B-stage sheet may include pulling a predeterminedamount of the composite sheet from a roll, cutting the sheet to thedesired dimensions, and/or removing a release sheet from the compositesheet prior to actual placing of the sheet 554 on the surface 556. Itwill be appreciated that where B-stage carbon fiber-reinforcedcomposites sheets are used to build the frame 515 and/or the pan 520,the support surface 556 may be clean and substantially free ofcontaminants that may later inhibit bonding of any components, such as,the brackets 58 and/or the clips 522 to the base or adjacent sheets. Asshown, additional sheets of the fiber-reinforced composite may be placedon the base sheet 554 until a predetermined number of sheets or aparticular thickness is reached.

Entrapped gasses from placing the sheets as well as volatile gases fromthe sheets may then be removed from the stack 550. Removal of entrappedgases may be referred to as “debulking.” Debulking may improve orincrease the contact between adjacent sheet surfaces and may improve thestrength of the resulting component. Debulking of the B-stage stack maybe completed at preset intervals during the laminating process and mayresult in a decrease in the overall thickness or height of the stack 550from before to after debulking. For instance, debulking may be completedafter each sheet is stacked onto the preceding sheet or may be completedafter every other sheet. The timing of the debulking process may varyaccording to the number of sheets stacked and the position of thosesheets on any preceding sheet.

With reference to FIGS. 10A and 10B, while the stack 550 may contain atleast two sheets, the stack 550 may be constructed of additional sheetsprior to debulking. By way of example, after the base sheet 554 and asubsequent sheet 558 are stacked, the stack 550 may be debulked byrolling or compressing the stack 550 (indicated by arrows in FIG. 10B).In addition, or as an alternative to rolling, the stack 550 may beexposed to vacuum to facilitate removal of any entrapped gasses. In oneembodiment, the stack 550 is placed in a vacuum bag (not shown) and avacuum (e.g., of about 14 psi) may be pulled on the bag. The stack 550is simultaneously rolled through the bag. By way of further example andas shown in FIG. 10A, three sheets 552 may be stacked prior todebulking.

As shown in FIG. 10C, once debulked, additional sheets 552 may be addedto the stack 550. The stack 550, including additional sheets 552, mayagain be debulked as described above. For example, where an initialstack contains three sheets and is debulked, as depicted in FIG. 10C, anadditional three sheets may be placed on the debulked three-sheet stack.The six-sheet stack may then be debulked to form a debulked, six-sheetstack 550. Accordingly, the process may include iteratively placing thesheets followed by debulking until the final stack includes thepredetermined number of sheets.

Additionally, with reference to FIGS. 11A-11D, in one embodiment,additional sheets of the fiber-reinforced composite may be cut to apredetermined shape prior to placing or stacking the sheet as set forthabove. With reference to FIG. 11A, additional sheets 560 and/or 562 maybe cut to a predetermined pattern different than the sheets 552. Thesheets 552, 560, 562 may be cut with scissors or a razor, for example.As such, each layer of the stack 550 may have the same or differentperipheral shape. By way of example, the pan 520 may be initiallyconstructed by placing multiple sheets on the base sheet 554 havingsubstantially the same peripheral shape. As is described above, thestack 550 may be debulked. Where, for example, the pan 520 is initiallyformed by a debulked stack of six sheets, additional sheets 560 and/or562 may be precut in an annular configuration and then stacked on thestack 550. By this process, as depicted in FIGS. 11A-11D, a rim orborder 564 may be formed on the initial six-sheet stack 550. Otherborders 566 may also be constructed. The stack 550, including theborders 564, 566 may then be debulked. It will be appreciated thatfollowing debulking, the edges of the stack 550 may not beperpendicular, as shown, rather the edges of the stack 550 and theborders 564, 566, for example, may be tapered. The borders 564, 566 may,following curing and machining, define the surfaces 535, 539 and/or theaccess ports 223-226 or 228. A similar process may be used to separatelyconstruct the frame 515.

Once the stack 550 is of sufficient thickness or contains thepredetermined number of sheets, it may be cured. Following curing, thecomposite may support mechanical loads. Curing of the debulked stack maytake place by heating the stack to an elevated temperature. Depending onthe fiber-reinforced composite composition, heating may occur in air ormay occur in a controlled atmosphere. By way of example, a debulkedB-stage stack of carbon fiber-reinforced composite sheets may be heatedto a temperature in excess of about 300° F. in air, such as, to about350° F. to cure the matrix. The heating process may take 24 hours andmay require longer or shorter times depending on the number of sheets inthe stack as well as other factors, for example, the composition of thematrix or the fiber. In one embodiment, the debulked stack is heated atabout 5° F. per hour to about 350° F. followed by slow cooling from thistemperature to room temperature.

Once cured, additional components may be secured, either via adhesive orother fastening means to the cured stack. As set forth above, thecomponents may include the brackets 58 and/or the clips 522 for the drippan 520 or the frame 515. The components may be secured prior tomachining operations, as set forth below, particularly where coolants orlubricants that would contaminate the surface of the cured stack areused during the machining process. Securing the components prior tomachining may improve the bond strength between the component and thecured composite.

In one embodiment, prior to adhesively joining the surface of the pan520 or the frame 515 is roughened such that the fibers of the compositeare exposed. The fibers may in some instances project from the surface.Various roughening processes may be used to expose and possibly cut thefibers, for instance, 40 grit sandpaper may be used to generate alocalized roughened area prior to application of the adhesive and thecomponent. The adhesive may therefore encapsulate the exposed ends ofthe individual fibers. When cured, the adhesive bond may include amechanical-type bond between the exposed fibers and the cure adhesive.

However, in one embodiment, the components, for example the clips 522and/or the brackets 58 may be placed on the surface 556 prior to initialplacement of the base sheet 554. In this regard, the support surface 556may be configured to accurately position components relative to thecured stack. For example, the surface 556 may include depressions (notshown) or another means for registering the position of those componentssuch that they are properly positioned on the pan 520 and/or frame 515following curing and machining. By this procedure, the components may bebonded to the stack during the curing process and may not require anyadhesive to bond the components thereto.

The cured stack may then be machined to form the sealing and othersurfaces thereof. For example, a carbon-fiber composite drip pan 520 maybe formed by machining the outwardly-facing peripheral surface 539 and acarbon-fiber composite frame 515 may be formed by machining theinwardly-facing peripheral surface 535 thereof. Other features of theframe 515 or pan 520 may be also be machined. Machining includes thoseprocesses whereby both portions of matrix and associated fibers areremoved from the cured stack. By way of example, machining may includeCNC machining and water-jet cutting processes. Water-jet cutting mayinclude ejecting pressurized water from a nozzle. The water may bepressurized to about 80,000 psi, for example, and may carry an abrasive,such as, 150 grit garnet. With reference to FIG. 8B, the surfaces 535and/or 539 may be cut with a water jet. And, for carbon fiber-reinforcedcomposite materials, water jet machining captures the carbon materialremoved from the cured stack thereby reducing or eliminating the hazardsassociated with machining carbon fiber reinforced composites.

Subsequently, with continued reference to FIG. 8B, the flanges 540, 544and o-ring stop 548 may be adhesively bonded to the core member 542 toform the pan 520. Alternatively, with reference to FIG. 8C, the recess546 may be machined via a CNC process in the surface 539 and then thebottom flange 540 may be secured thereto to form the pan 520. Acombination of water jet cutting and CNC machining may also be used toform the surfaces 535, 539 as well as other features of the frame 515and/or the pan 520.

In one embodiment, the drip pan 520 and the frame 515 are constructed ofa single stack of fiber-reinforced sheets. By way of example, both thedrip pan 520 and the frame 515 may be made from a single stack of carbonfiber-reinforced composite sheets. The single stack may be built as setforth above and then each of the pan 520 and the frame 515 may bemachined from that single stack. In this exemplary process, eachindividual sheet in the stack may be cut to a predetermined shape priorto placement as described above. In other words, each sheet may have thesame or different peripheral shape. By varying the peripheral dimensionsof each sheet, the cross sectional profile of the stack may be variedwith relatively thick and relatively thin regions as is shown by way ofexample in FIGS. 11A-11D.

For example, the frame 515 and the border of the pan 520 may be built upto be the same number of sheets thick. The central portion of the pan520, however, may be much thinner and require fewer sheets. In addition,other features, such as the access parts, may be formed by placingsheets having different peripheral shapes on a specific region of thestack 550. While the stacking process may begin with the cabin-facingportion of the drip pan apparatus 500 and end with thetransmission-facing surface of the apparatus 500, it will be appreciatedthat the process described herein is not so limited. In other words, thepan 520 and/or frame 515 may be constructed by placing sheets that formthe transmission-facing surface first and the cabin-facing surface last.In this embodiment, it may be necessary to first obtain a cast or mold(not shown) of the desired transmission-facing surface and place precutsheets accordingly. For example, the border of the pan 520 may beinitially built by cutting annular rings of the B-stage sheets and thenplacing those annular rings on one another in a recess in the moldconfigured to form the border. Once the border region is stacked anddebulked, if necessary, the remaining sheets of the pan 520 that are toform the cabin-facing side of the pan 520 may be cut and placed on theannular ring. This portion of the pan 520 may be supported by a raisedportion of the mold surface. However, once the stack 550 is cured, theframe 515 and the pan 520 may be machined from the single sheet.

With reference to FIGS. 12A-12F, in this embodiment, the water-jetcutting process may be used to cut the cured stack. To that end, one ormore pilot holes 568 may be drilled through the cured sheet. The waterjet cutting process may then begin at the pilot hole and be directed ina predetermined direction to cut the cured stack substantiallyperpendicular to the outer surfaces thereof to form the pan 520 andframe 515.

Specifically, with reference to FIGS. 12A-12F, in one embodiment, themachining process may include drilling of the pilot holes 568, thenwater jet cutting the covers 70, view window 236, frame 237, and accessports 223-226 and 228 from the corresponding pilot hole 568. Adonut-shaped core 570 (FIG. 12B) may be formed during cutting of each ofthe access ports 223-226 and may be removed. With reference to FIG. 12C,the outwardly-facing peripheral surface 539 may then be cut from one orpilot holes 568. The core member 542 may then be removed. Theinwardly-facing peripheral surface 535 may then be cut as depicted inFIG. 12D. A core 572 may be formed and may be removed. With reference toFIGS. 12E and 12F, the outer periphery 574 of the frame 515 may then becut such that each of the frame 515, pan 520, and covers 70, as well asother features, are cut from the single cured stack. It will beappreciated that while a particular order for machining may be inferredfrom the above description, the order in which the machining iscompleted may be reversed or be made in any combination.

Because the water-jet process may produce a generally cone-shaped waterjet, the nozzle or orifice of the water-jet machine may be tiltedslightly. Slight tilting of the nozzle may provide a cut surface that issubstantially perpendicular with the plane of the frame 515 and/or pan520. It will be appreciated the frame 515 and/or pan 520 may be cut fromthe transmission-facing surface to the cabin-facing surface or viceversa. It will also be appreciated that machining the cured stack mayinclude machining with both a water jet process and a CNC machiningprocess. For instance, the surfaces 535, 539 may initially be cut via awater-jet process and then machined on a CNC machine. It will beappreciated that unlike a water-jet cutting process, which may cut thecomposite cross wise to form the surfaces 535, 539, the CNC machiningprocess may be used to machine all or a portion of the surface 535, 539longitudinally or with the surfaces 535, 539.

In one embodiment, additional sheets of the composite or anothermaterial may be secured or adhesively bonded to the cabin-facing sideand the transmission-facing side of the machined stack 550 to form theframe 515 or pan 530. These additional sheets may form the bottom flange540, the top flange 544, and/or the o-ring stop 548 of the pan 520. Anexemplary adhesive includes Resinlab® EP 1238 epoxy adhesive, a two-partacrylic/epoxy hybrid adhesive commercially available from EllsworthAdhesive Company of Germantown, Wisconsin. The adhesive may wet thecarbon fiber-reinforced composite and may have flexibility or resiliencywhen cyclically loaded. In one embodiment, shown in FIG. 8B, theadhesive forms a fillet 549 between the corresponding adhesively bondedcomponents, such as, between the o-ring stop 548 and theoutwardly-facing peripheral surface 539 and/or between the o-ring stop548 and the bottom flange 540. As such, the adhesive may form a portionof the surface 539. In addition, carbon fiber-reinforced rivets (notshown) may be forced into holes machined in the bottom flange 540 and/orthe top flange 544 and into the core member 542. A portion of the rivetmay extend into the flange 540, 544 and the core member 542. The rivetsmay further strengthen the bond between the respective flange 540, 544and the core member 542.

With reference to FIG. 9, the seal member 222 forms a fluid tight sealwith the inwardly-facing and with outwardly-facing peripheral surfaces535, 539. As is set forth in the embodiments above, one or both of thesesurfaces may be formed by machining the cured stack. In other words, thesurfaces 535, 539 may not be as-formed surfaces. Rather, they may eachbe formed by removing both matrix material and fiber. As such, thesesurfaces 535, 539 may be rough when compared to a metal surface machinedfor the purpose of forming a fluid-tight seal. And, due to the nature ofthe composite, the roughness of the surfaces may not be capable of beingreduced in a cost-effective and/or efficient process. The machinedsurface may therefore include exposed end portions of cut fibers.

In one embodiment, the surfaces 535, 539 do not receive any additionalmachining or treatment prior to installation of the apparatus 500 in thehelicopter 10. By way of example, the roughness of the machined surfaceswith which the seal member 222 contacts, e.g., the inwardly-facingand/or outwardly-facing peripheral surfaces 535, 539, may be at leastabout 16 micro-inches (rms) or at least about 32 micro-inches (rms) and,by way of further example, may be at least about 63 micro-inches (rms).By way of example and not limitation, the seal member 222 may have adurometer hardness of about 70 Shore A. However, even where one or bothsurfaces 535, 539 are cut as set forth above and are characterized bysurface roughness higher, and in some case substantially higher, thanthat used to form fluid-tight seals with metal surfaces, once installedand in operation, the drip pan apparatus 500 seals the access opening205 from uncontrolled fluid leakage therethrough. For example, surfaces535, 539 in conjunction with seal member 222 substantially preventleakage of fluid between the pan 520 and the frame 515. The seal formedmay prevent fluid leakage when subject to a fluid pressure generated byhydraulic fluid of about 1 inch in depth on the drip pan 520.Furthermore, the seal formed may resist or prevent leakage while beingsubject to normal vibration during operation of the helicopter 10.

In an alternative embodiment, one or both of the frame 515 and the drippan 520 are monolithic fiber-reinforced composites. In other words, theframe 515 and the drip pan 520 may be molded by vacuum molding orcompression molding techniques in a mold (not shown). The mold mayinclude a cavity generally defining the frame 515 or the drip pan 520.The fiber-reinforced composite may be placed in the mold and compressedor vacuum formed with or without heating to individually form a preformhaving a configuration of the frame 515 or the drip pan 520. Onceformed, such a preform may be subject to a similar curing process as setout above. The formed and cured preform may then be machined. Forexample, the preform may be machined to form the outwardly-facingperipheral surface 539 or the inwardly-facing peripheral surface 535. Byway of further example, it may be necessary to drill holes in the tabs202 through which fasteners 201 may pass. The pan 520 and/or frame 515may also be machined from a block of the composite. However, it will beappreciated that such processes may be characterized by a large amountof waste and a pan or frame of relatively poor strength.

As described above, routine maintenance and inspection of the rotortransmission 16, may not ordinarily require removal of the entire drippan for any of the apparatuses 300, 400, or 500. As shown in FIGS. 2Aand 2B, to accommodate limited access for routine maintenance orinspection, or filter replacement, removable access covers 70 areprovided in drip pan 320, 420, or 520 to allow access through accessports 223, 224, 225, 226, 228 (collectively referred to herein as“access ports”) to mechanical linkages in and around the rotortransmission and to allow inspection of the fluid levels associated withthe rotor transmission 16.

To secure access cover 70 to the access ports in, for example, any ofdrip pans 220, 320, 420, and 520, each access cover 70 may have aresilient member 74 which functions much like resilient member 50 forsecuring the drip pans 220, 320, 420, and 520 to one or another of theframes 215, 315, 415, or 515. To facilitate the removal of access covers70 from access ports, pull handles 90 may be attached to access covers70. Fasteners 92 may fixedly secure pull handles 90 and/or members 74 toaccess covers 70.

As an alternative to the access cover 70 and with reference to FIGS. 2A,13, 14, and 15 there is illustrated a drain port assembly 600. As isshown specifically in FIG. 2A, in one embodiment, the drain portassembly 600 may be removably disposed in sealing engagement withinaccess ports 224 and 226. In this regard, it will be appreciated thatthe drain port assembly 600 may be removably disposed in all of, or aselected few of, the access ports disclosed herein.

With reference to FIG. 2A, ports 224 and 226 are generally positionedclosest to the flight deck or cockpit and are thus generally located onthe opposite side of the special operations equipment (e.g., the FRIES30 or the medevac bar 40 shown in FIGS. 3A and 3B, respectively) fromthe drain line 104. This is best illustrated in FIG. 3B.

With reference to FIG. 3B, drain tubes 106 may be connected to each ofthe drain port assembly 600 as well as to the drain 100. The tubes 106may divert fluids to another location, such as, outside of the cabin 12.Typically, to do so, the tubes 106 are secured to the ceiling of thecabin 12 at one or more locations other than to the drain line 104. Assuch, fluid that drips from the transmission 16 or from another locationabove cabin 12 may be provided with multiple pathways by whichaccumulation of fluid on the drip pan apparatus 200, 300, 400, or 500may be minimized or avoided.

In prior pans, the existence of fixed drain lines on each side of thespecial operations equipment created problems with removal of the panbecause the drain lines would interfere with sliding of the pan ineither direction for maintenance purposes. Advantageously, the drainport assembly 600 allows additional drain ports to be added to theapparatus 200, 300, 400, 500 though the addition of a drain port doesnot interfere with the removal of the drip pan from the frame. Moreover,the drain port assembly 600 eliminates the necessity of disconnectingthe drain tube 106 therefrom prior to removal of the pan.

For example and with reference to FIGS. 2A, 3B, according to oneembodiment of the invention, the drip pan 220 may be removed from theframe 215 by initially removing each drain port assembly 600. Removal ofthe pan 220 may then proceed without first disconnecting the tube 106from the drain port assembly 600. In this manner, once the drain portassembly 600 is removed, the drip pan 220 may be slid aft between themedevac bar 40 and the corresponding frame 215. The drip pan 220 maythus be completely removed to provide full access through opening 205.The removed drain port assemblies 600 may be allowed to hang or danglefrom their respective tubes 106 during maintenance. As such, they remainattached to the helicopter 10, even when the associated pan is removed.

To that and other ends, and with reference now to FIGS. 13, 14, and 15,one embodiment of the drain port assembly 600 is shown and includes aport cover 602 that may have an annular groove 604 configured to receivea seal member 606 therein for sealing engagement with one of the accessports defined by a drip pan, described above. The port cover 602 definesan opening 608 therethrough. The assembly 600 further includes a draincap 610, which may be integral with or secured to the port cover 602 by,for example, adhesive, sealant, and/or fasteners 612. The drain cap 610may be generally configured with a hat-like cross-sectional shape, asshown. However, the cap 610 may be truncated or partially tapered alongone side thereof. For example, the cap 610 may have a side wall 614 withan enclosed end 616. A slanted wall 618 may extend from the side wall614. By way of example, the slanted wall 618 may intersect the enclosedend 616 at about 45 degrees. The side wall 614 may define a drain 620 towhich the drain line 104 may be secured. It will be appreciated thatdrain 100, shown in FIG. 2A, may be configured with the drain cap 610 inplace of the cap shown.

The drain cap 610 is generally aligned with the opening 608 whereby,when the assembly 600 is removably inserted into a drip pan, describedabove, fluids may be directed through the assembly 600 to a locationoutside of the cabin 12. It will be appreciated that the configurationof the cap 610 including the slanted wall 618 may be oriented within thecabin 12 to improve clearance therein. For example, the slanted wall 618may allow more head room for personnel who are in the cabin 12 or theslanted wall 618 may be selectively positioned to face specialoperations equipment attached to the ceiling of the cabin 12 and providemore clearance therebetween.

In addition, in one embodiment as shown in FIGS. 14 and 15, the drainport assembly 600 may further include a grate 622. The grate 622 mayreduce plugging of the tubes 106 by preventing relatively large debrisfrom entering the corresponding drain line 104. With reference to FIG.14, the grate 622 may be positioned on the cabin side (between the cap610 and the cover 602) of the port cover 602. However, it will beappreciated that the grate 622 may be placed on the transmission side ofthe port cover 602. Other strainer-like configurations are possibleincluding a strainer that is integral with the cap 610 or with the portcover 602.

With reference to FIGS. 16 and 17, in one embodiment of the invention,there is shown a drain port assembly 700. The drain port assembly 700 isconfigured to removably engage the access ports, similar to that of thedrain port assembly 600. Resilient members 74 engage a recess formed inthe corresponding access port to releasably secure the drain portassembly 700 to the drip pans 220, 320, or 420, or member 74 mayreleasably secure the assembly 700 to clips 522 for pan 520.

Similar in function to the drain port assembly 600, set forth above, thedrain port assembly 700 includes a port cover 702. A drain pipe 704 mayextend through the port cover 702 such that fluid passing throughgrating 706 may be directed away from the cabin 12 of the helicopter 10.When present, a drain washer 708 may surround and reinforce the portcover 702 in the vicinity of the drain pipe 704. A drain support 710 mayextend between the port cover 702 and the drain pipe 704 to reinforcethe drain pipe 704.

Assembly 700 may include clips 712 for securing resilient member 74thereto. The clips 712 may alternatively secure a buckle 714 to the portcover 702. As shown in FIG. 8, the buckle 714 may releasably secure apull handle or strap 716 to the assembly 700 at one end thereof. Anotherbuckle 714 at the other end of the strap 716 may be secured to the drippan 220, 320, 420, 520. As shown, placement of the buckle 714 may benear a peripheral edge of the port cover 702. Another buckle 714, alsosecured to the strap 716, may be attached to the associated pan in aposition whereby the strap 716 generally crosses the port cover 702.This orientation of the strap 716, which crosses the assembly 700, mayreduce the force needed to remove the assembly 700 from the pan 520. Inaddition, the relative, asymmetrical orientation of the clips 522 andthe resilient members 74 assure that the relative orientation of theport cover 702 and the pan 520 will keep the assembly 700 oriented inthis manner. In other words, the assembly 700 may be installed in thepan 520 in a single orientation. The configuration including the strap716 may eliminate the need for both the pull handle 90 and the lanyard82 (shown in FIG. 2A) thereby reducing the relative weight of theassembly 700, allowing easy replacement of the assembly 700 and/or strap716, and keeping the port cover 702 attached to the pan when the portcover 702 is removed therefrom.

The port cover 702 further includes a port ring top 717 and a port ringbottom 718 that may partially define recess 720 adapted to receive asealing member or o-ring 719. Recess 720 may also be partly defined byan o-ring stop 722 that is configured to increase the surface area forsecuring the port ring top 717 to the port cover 702.

In one embodiment, the port cover 702 may be made by a laminatingprocess similar to that described above with regard to the drip panapparatus 500. In this regard the port cover 702 may include a stack ofat least two sheets of the fiber-reinforced composite. In oneembodiment, the port cover 702 includes 6 sheets of a carbonfiber-reinforced composite, and the port cover 702 is made by a similarprocess as set forth above with regard to the drip pan 520 and/or frame515. In this regard, the port cover 702 may be constructed by initiallyforming a stack of uncured fiber-reinforced composite sheets, forexample, B-stage carbon fiber-reinforced composite sheets. As with thepan 520 and/or frame 515, a base sheet may be initially placed onto asupport surface. Additional sheets may then be placed on the base sheet.The stack may be debulked, as set forth above.

Once the stack contains a predetermined number of sheets, it may becured. Following curing, the clips 712 and/or buckles 714 may beattached thereto by appropriate adhesive as set forth above. The clips712 and/or buckles 714 may also be made of the reinforced compositethough they may be made of stainless steel, titanium, or titaniumalloys. In one embodiment, the drain pipe 704 may also be made of thefiber-reinforced composite and may be adhesively secured to the portcover 702. In one embodiment, the cured stack may be machined. Forexample, the recess 720 may be machined from the cured stack.

In one embodiment, as set forth above with reference to FIGS. 12A-12B,the port cover 702 may be cut from the same cured stack as the pan 520.To this end, following curing of the stack 550 that is to form the pan520, one or more of the port covers 702 for each access port 223, 224,225, 226, 228 may be cut from the stack at a predetermined location. Inthis regard, two cuts may be required to cut the port cover 702 and thecorresponding access port from the pan 520. One cut may be required todefine the port cover 702 and an additional cut may form thecorresponding access port. The two cuts may be spaced apart and thusform an annular ring of material that may then be removed. While twocuts are described, it will be appreciated that a single continuous cutthat first forms the port cover 702 and then forms the correspondingaccess port is also contemplated. The distance between the cut surfacesmay be about 0.100 of an inch though the distance may depend on thedimensions of the seal member that may be used to form a seal with theopposing surfaces.

In one embodiment, a pilot hole may be initially drilled through thecured stack. At set forth above with regard to FIGS. 12A-12F, thelocation of the pilot hole may correspond to be within the annular ringthat remains once each of the port cover 702 and the access port is cutinto the pan 520. A water-jet may then be used to cut the port cover 702and the corresponding access port starting at the pilot hole. It will beappreciated that both surfaces with which an o-ring may form a seal arecut or machined surfaces. The surfaces formed by cutting may be rough,for example, at least about 16 micro-inches (rms) or at least about 32micro-inches (rms) or more. Nevertheless, the o-ring may form a fluidtight seal with each such that when the assembly 700 is inserted intothe corresponding access port, the seal member forms a fluid-tight sealtherebetween. It will be appreciated that while the assembly 700 isdescribed as being manufactured by a layering or stacking process, theassembly 700 may be machined from a single piece of the fiber-reinforcedcomposite.

With reference now to FIGS. 18-20, alternative embodiments forattachment of other components to one or all of the frame 515, pan 520,and port cover 702 are shown. It is known that attachment of componentsby adhesive bonding or fasteners to cured fiber-reinforced compositematerials may be result in relatively low bond strength. This may beparticularly true when components are bonded to carbon fiber-reinforcedcomposites after curing. It is known that minute amounts ofcontamination on the surface may dramatically reduce the bond strengthof the adhesive at those locations. For example, an adhesive bondbetween the clip 522 and the frame 515 may be relatively weak due tocontamination between the adhesive and the frame 515. Thus, the bondstrength may be less than that required during use of the frame 515. Tosolve the contamination problem, it is known to construct a dedicated“clean room” and similar environments from which known contaminants areexcluded. However, installation and maintenance of a clean roomenvironment is expensive both in terms of capital and operating costs.

As an alternative to clean rooms, in one embodiment of the invention, abracket 800 may be mechanically secured to the fiber-reinforcedcomposite. The bracket 800 shown in FIGS. 18, 19, and 20 may represent aclip 522, a clip 712, and/or a buckle 714 shown in FIGS. 2A, 8, and 16,for example. The bracket 800 may be configured to be secured to theframe 515, for example, by a mechanical or interference typearrangement. This bond may not rely completely or even predominantly onthe tensile and/or shear strength of an adhesive to retain the clip 522secured to the frame 515 or pan 520.

By way of example, and with reference now to FIG. 18, the bracket 800may be configured with two J-shaped extensions 802 that extend laterallyfrom legs 804. The extensions 802 are inserted into correspondingL-shaped through-holes 806 formed in the frame 515, for example. Thoughnot shown, the legs 804 of the bracket 800 are resiliently biasedoutward as indicated by the arrows in FIG. 18. To insert the extensions802 into the through-holes 806, the extensions 802 may be squeezedtogether or inserted in another manner in which the J-shaped extensions802 are positioned to cooperate with the L-shaped through-holes 806.Once positioned, the legs 804, which are biased outward, maintain theJ-shaped extensions 802 in a position that resists forces tending topull the bracket 800 from the frame 515. In this regard, the J-shapedextensions 802 create an interference with the frame 515 such that itresists removal of the bracket 800 from the frame 515. Any clearancebetween the legs 804 and extensions 802 may be filled with a sealant,such as, PROSEAL™ as set forth above or a wedge of material (not shown)may be used to partially fill any clearance between the legs 804 and theframe 515. The bracket 800 may be made of metal or plastic or anothermaterial. In this manner, materials for bracket 800 that would nototherwise form a strong bond with the cured composite may be used.Furthermore, the bracket 800 may have a rectangular or roundcross-sectional configuration. As such, the bracket 800 may be cut froma straight resilient wire or resilient flat stock and then bent into aconfiguration, such as, the configuration shown.

By way of additional example, and with reference to FIG. 19, the bracket800 may include legs 812 having lateral extensions 814 extendinggenerally perpendicular to legs 812. The extensions 814 may extendlaterally to a greater distance than the J-shaped extensions 802 shownin FIG. 18. However, the legs 812 of bracket 800 shown in FIG. 19 maynot be outwardly biased and therefore may not forcibly contact the frame515 following installation thereof A through-hole 816 may include alateral extension 818 that is configured to receive extensions 814.Through-hole 816 may be defined in part by a plug 819. In this regard,following insertion of the bracket 800 in the frame 515, the plug 819 isinserted. In addition, following insertion of the plug 819, a sealantmay be used to seal any space between the legs 812 and the frame 515 andthe legs 812 and the plug 819 to inhibit leakage of fluid therethrough.

By way of yet another example, and with reference to FIG. 20, thebracket 800 may have a pin 820 (e.g. a roll pin) secured or through eachleg 812. Corresponding openings 822 may be machined in the frame 515.These openings 822 may be configured to receive the legs 812 along oneportion thereof and the pin 820 in another portion thereof Thus, theopenings 822 together with the pin 820 are configured to create aninterference fit between the bracket 800 and the frame 515. Thisconfiguration resists removal of the bracket 800 during usage thereof.While FIG. 20 illustrates the pin 820 recessed within a portion ofopening 822, embodiments of the invention are not so limited. Theopening 822 may extend uniformly through the frame 515 such that aninterference fit may be generated with the surface of the frame 515. Inaddition, although not shown, the pin 820 may be non-linear to resistunintentional pullout from the leg 812. For example, each end of the pin820 may be bent or angled relative to a central portion. When inserted,the central portion may pass through the leg 812. The bent or angledportion may then provide a mechanical interference with the hole in eachleg 812. The pin 820 may, therefore, require pulling or pushing at anangle relative to the leg 812 to withdrawal the pin 820 from the leg812.

Furthermore, it will be appreciated that while reference is made to theframe 515 in conjunction with the bracket 800, the bracket 800, shown inany of FIGS. 18-20, may be used in conjunction with an opening machinedin the drip pan 520 and/or any of the port covers 702. Further in thisregard, a broken or otherwise non-functional bracket may be replacedwhen the helicopter is in the field simply by removing the sealant,withdrawing the non-functional bracket, inserting a new bracket 800, andsealing any clearance between the bracket 800 and component.

While the present invention has been illustrated by the description ofembodiments thereof, and while the embodiments have been described inconsiderable detail, they are not intended to restrict or in any waylimit the scope of the appended claims to such detail. Additionaladvantages and modifications will readily appear to those skilled in theart. The invention in its broader aspects is therefore not limited tothe specific details and drawings shown and described. Accordingly,departures may be made from such details without departing from thescope of the general inventive concept.

1. A drip pan for cooperation with a frame for covering an access opening to a rotor transmission of a helicopter, the frame having a seal surface, the drip pan comprising: a substantially planar member comprising a fiber-reinforced composite and having a seal surface that is configured to cooperate with a seal member disposed between the substantially planar member and the frame to form a fluid-tight seal between the seal surface of the substantially planar member and the seal surface of the frame to seal the access opening from fluid leakage.
 2. The drip pan of claim 1, wherein the seal surface of the substantially planar member includes a machined surface.
 3. The drip pan of claim 2, wherein the machined surface includes a water jet cut surface.
 4. The drip pan of claim 1, wherein the seal surface has a surface roughness of at least about 16 micro-inches.
 5. The drip pan of claim 1, wherein the seal surface includes exposed end portions of cut fibers that are configured to contact the seal member.
 6. The drip pan of claim 1, wherein the substantially planar member includes a core member of a plurality of sheets of a fiber-reinforced composite material stacked together and cured, the core member having at least one machined surface forming at least a portion of the seal surface.
 7. A drip pan apparatus for use on a helicopter having an airframe member defining an access opening, a skirt secured to the airframe member around the periphery of the access opening, the drip pan apparatus comprising: a frame comprising a fiber-reinforced composite and including an inwardly-facing peripheral surface, the frame being adapted to be secured to the skirt; a drip pan comprising a fiber-reinforced composite, defining an access port, and having an outwardly-facing peripheral surface that is configured to cooperate with the inwardly-facing peripheral surface of the frame, wherein at least one of the inwardly-facing peripheral surface and the outwardly-facing peripheral surface is a machined surface; and a seal member configured to be disposed between the inwardly-facing peripheral surface and the outwardly-facing peripheral surface and to form a fluid-tight seal between the drip pan and the frame.
 8. The drip pan of claim 7, wherein the frame and the drip pan each include a core member of a plurality of sheets of a fiber-reinforced composite material stacked together and cured, each core member having at least one machined surface configured to form a fluid-tight seal with a sealing member engaging the machined surface.
 9. The drip pan of claim 8, wherein the number of sheets in the core member of the frame is the same as the number of sheets in the core member of the drip pan.
 10. A drip pan apparatus for use with a helicopter having a cabin section, a rotor transmission oriented at least in part above the cabin section, a rotor transmission access opening defined by an airframe member of the helicopter in the ceiling of the cabin section, a skirt secured to the airframe member around the periphery of the access opening, and a wire bundle between the rotor transmission and the cabin section, the drip pan apparatus comprising: a frame adapted to be attached to the skirt, the frame having an inwardly-facing peripheral surface; a drip pan configured to cooperate with the frame and having an outwardly-facing peripheral surface; and a seal member disposed between the outwardly-facing peripheral surface and the inwardly-facing peripheral surface, wherein at least one of the frame and the drip pan has a discontinuous edge structure configured to face the transmission to accommodate the wire bundle proximate the frame and/or the drip pan when the frame is attached to the helicopter and the drip pan is removably secured to the frame.
 11. The drip pan apparatus of claim 10, wherein the discontinuous edge structure includes a groove extending along a limited length of a peripheral edge of the drip pan, the groove being configured to face the wire bundle when the pan is installed in the frame.
 12. The drip pan apparatus of claim 10, wherein the discontinuous edge structure includes a recess formed in the frame that defines a thickness of the frame that is less than a thickness of the frame in a region adjacent the discontinuous edge structure, the recess being configured to face the wire bundle when the frame is installed on the skirt.
 13. The drip pan apparatus of claim 10, wherein the frame has an inner rim that is configured to face the rotor transmission and a recess is formed in the inner rim so as to extend across the width of the inner rim, the thickness of the frame from the recess to an opposing surface of the frame being less than the thickness of the inner rim to the opposing surface, the recess being configured to face the wire bundle when the frame is installed on the skirt.
 14. The drip pan apparatus of claim 10, wherein when the drip pan is installed in the frame, the outwardly-facing peripheral surface of the drip pan is exposed to the rotor transmission in the region of the discontinuous edge structure.
 15. A method of removing a drip pan from a helicopter having a cabin section, a rotor transmission oriented at least in part above the cabin section, a rotor transmission access opening in the ceiling of the cabin section, special operations equipment spanning the access opening, and a drip pan apparatus covering and sealing the access opening, the drip pan apparatus having a drip pan detachably secured to a frame, the drip pan including a first drain line coupled to a first drain tube that is attached to the helicopter at a first location, a drain port assembly detachably secured to the drip pan and including a second drain line coupled to a second drain tube that is attached to the helicopter at a second location, wherein the special operations equipment is positioned between the first drain line and the second drain line, such that movement of the drip pan causes the special operations equipment to interfere with one of the first or second drain lines, the method comprising: detaching the drain port assembly from the drip pan to expose an access port, the drain port assembly remaining coupled to the second drain tube and attached to the helicopter at the second location; releasing the drip pan from the frame; and sliding the drip pan in a direction that moves the access port between the special operations equipment and the rotor transmission to remove the drip pan from the frame.
 16. The method of removing the drip pan of claim 14, wherein the first drain tube remains coupled to the first drain line during sliding of the drip pan to remove the drip pan from the frame.
 17. A method of making a drip pan apparatus for a helicopter having an airframe member defining an access opening and a skirt secured to the airframe member around the periphery of the access opening, the method comprising: placing a plurality of sheets of an uncured fiber-reinforced composite material on one another to form an uncured stack; curing the uncured stack; and cutting a frame and a drip pan from the cured stack, wherein cutting the frame forms an inwardly-facing peripheral surface and cutting the drip pan forms an outwardly-facing peripheral surface, the inwardly-facing peripheral surface and the outwardly-facing peripheral surface each configured to sealingly engage a seal member and form a fluid-tight seal therebetween.
 18. The method of claim 17, wherein placing the plurality of sheets includes placing a base sheet and then placing a sheet with a different predetermined peripheral configuration than the base sheet on the base sheet.
 19. The method of claim 17, wherein cutting the frame and the drip pan includes cutting the drip pan from a region of the cured stack within the region of the cured stack from which the frame is cut.
 20. In combination: a multi-passenger helicopter comprising: a flight deck; a cabin section rearward of said flight deck; a rotor transmission oriented at least in part above said cabin section; and a transmission access opening within said cabin section for providing access to said rotor transmission; and a drip pan apparatus for covering said transmission access opening, said drip pan apparatus comprising: a frame adapted to mount to said transmission access opening, said frame having an inwardly-facing peripheral surface extending around said frame; a drip pan having an outwardly-facing peripheral surface extending around said drip pan; and a seal member disposed between said inwardly-facing peripheral surface and said outwardly-facing peripheral surface, wherein one of the frame or the drip pan or both the frame and the drip pan comprise a fiber-reinforced composite. 